2018 GMC SIERRA 1500 Complaints

When driving the transmission will shift hard almost jumping forward, especially from a stopped position into 1st.

The contact owns a 2018 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed and depressing the accelerator pedal, the vehicle failed to accelerate as intended. The message "Reduced Power" was displayed, and the RPMs increased. Additionally, the vehicle jerked, and the contact noticed that there was smoke coming out of the exhaust pipe. The vehicle was driven to the contact's residence. The vehicle was taken to an independent mechanic, where it was diagnosed that the starter, the battery, the fuel pump, the oil pump, the oil pump sensors, and the fuel injectors had failed and needed to be replaced. The vehicle was repaired; however, the failure reoccurred. The contact stated that while driving at an undisclosed speed, the vehicle stalled. There was no warning light illuminated. The vehicle was able to restart; however, the failure recurred. The vehicle was driven to the contact's residence. The vehicle was not repaired. The manufacturer was made aware of the failure, but no assistance was provided. The failure mileage was approximately 133,742.

I am the original owner of a 2018 GMC Sierra 1500 with the 6.2L L86 engine and 8-speed 8L90 transmission. I began experiencing severe transmission shuddering and harsh shifting, especially at lower speeds or under light acceleration. When the issue occurs, I press the gas and the engine revs up to 6,000 RPM without reaching 20 MPH, making it extremely difficult — and dangerous — to merge into traffic or cross intersections. This issue has worsened over time and is now a critical safety concern, especially with children in the vehicle. I have researched this issue and found that many owners report the same transmission defect, and there is an open class action lawsuit and a GM Technical Service Bulletin (TSB #18-NA-355) describing the exact symptoms. The vehicle has become unsafe to drive. GMC should issue a recall or mandatory repair program for this known defect before someone is injured or killed.

Engine lifters failed. Heard ticking noise first day truck was purchased that gradually got louder but was told by gmc service shop it was normal to hear the ticking noise. Also when cruise control is on and you are decending a hill the rpms raise and you lose engine compression this will cause your speed to drop to around 20 mph and has happened nunerous times.. as well when making a turn sometimes or just driving the vehicle turns off while in motion and you have to coast to the side of the road and turn the key off and back on to start driving agsin.. the loss of power is a complete blackout no dash.. no engine nothing. As result of the lifter issue the engine also hard shifts in and out of slow gears.. I have not driven my truck in about a year and still owe 22k on it. The issues with this vehicle are the same as the recalled 6.3 v8 engines.

My vehicle was a well maintained 2018 GMC Sierra 1500. It has 58000 miles. I was driving in 30 mph zone thank God. Heard a loud boom and the truck lost power and shut off. I got out and oil was pouring out. I took it to the GMC dealership and they told me the engine failed. They didn’t know why or what caused the failure. But said they is a hole in the block and all they can say is something in the engine failed.

The contact owns a 2018 GMC Sierra 1500. The contact stated that while depressing the brake pedal, the brake pedal displayed more resistance than expected, causing the contact to have to apply more pressure while depressing the brake pedal. The contact stated that the braking distance was extended due to the failure. The vehicle was taken to the dealer who diagnosed that the brake vacuum pump had failed and needed to be replaced. The vehicle was not repaired. The contact became aware of NHTSA Campaign Number: 19V645000 (Service Brakes, Hydraulic); however, the VIN was not included. The manufacturer was informed of the failure and confirmed that the VIN was not included in the recall. The manufacturer referred the contact to the NHTSA Hotline to report the failure. The failure mileage was approximately 75,000.

The contact owns a 2018 GMC Sierra 1500. The contact stated that while driving at various speeds, while depressing the brake pedal to slow down, the brake pedal lost pressure, and the vehicle experienced a reduction in braking power. The contact had to depress the brake pedal with additional force to properly slow the vehicle. There was no warning light illuminated; however, the message "Brake Assist" was displayed on the instrument panel. The local dealer was not contacted, and the vehicle was not diagnosed or repaired. The manufacturer was not notified of the failure. The approximate failure mileage was 135,000.

GM has discontinued a critical engine belt on the 2018 GMC Sierra 1500 5.3L eAssist. This makes the truck undrivable and unsafe to own, even though the vehicle is still under financing and only 7 years old. There is no available part, and no alternative has been offered by the manufacturer.

Apparently, GMC began using soy-based wire coatings approximately 10 years ago. The wiring harness on my vehicle has literally been eaten and destroyed by squirrels causing the entire electrical system to be compromised. Safety features have been especially affected including but not limited to air bags, windows being inoperable, door locks being stuck open or closed without a physical key, stabilitrak system arbitrarily shutting off, and windshield wipers working intermittently. Obviously, these are critical systems for the safe operation of this vehicle for the driver, passenger, and members of the public that share the roads. I have had the main harness repaired at a dealership (paid by insurance) but it remains an ongoing safety and financial issue. The dealership identified other portions of the electrical system still need repair and may further compromise safety. Not only were warning lights activated, approximately 10 in-dash messages were displayed warning of malfunction prior to dealership inspection and partial remediation.

The transmission would purge forward when shifting gears. The shifting was very rough. This vehicle had recently been in accident.